Safety inner tube



3&1942- v a s. PIDGEON g@ SAFETY INNER TUBE Filed Dec. 7. 1939 INVENTOR ATTONEYS concentric annular chambers, one arranged inside oi the other and having a passage in the wall separating one chamber from the other, said passage having an effective cross sectional area at least substantially as great as that of the inflating means,'a iiap valve associated with said passage adapted to normally remain open but responsive to a pressure differential between said chambers and/or centrifugal force to reduce the eiective cross section of said passage to thereby control the rate of ilow therethrough.

A still further object is to provide a valve as aforesaid on the inside of the wall between the two chambers which is provided with a weight, which causes the valve to operate` to restrict the vpassage when the wheel is operated above a pre determined speed, regardless of a pressure difierential existing between the chambers, whereby at such speed, and above, the valve is automatically held in closed position as a safety measure before any pressure differential develops as a resuit of a blowout or puncture and which valve will be open again when it is desired to deflate the tire as when demounting, or to inflate the tube.

Other objects will be manifest as the specication proceeds.

AOi the accompanying drawing:

Figure 1 is a perspective view of a safety inner tube embodying the invention, a part being broken away to reveal the improved safety valve therein;

vided for the inflation and normal denation of the inner tube. Said valve stem is located in the inner circumference of the inner tube. either in the medial plane of the tube or somewhat to one side thereof as shown. The valve stem opens into the inner compartment Il of the inner tube. and preferably is locaedl80" from the aperture li in the inner structure il.A ,v

Whiie'the innertube is being inflated through the agency ofthe aforesaid valve stem It, it

is desirable that the air pass readily through the aperture or port il, from the inner chamber I3 to the outer chamber i4, to provide uniform pressure in k both chambes. In the event of a blowout it i'sequaliy desirable that passage oi air through-said port be retarded. so that the vehicle will be supported by the air in the inner chamber for a sufiicient interval of time as will enable the vehicle to be brought under control and brought to a stop. To this end the port I! is provided with'a 4valverneemlcer" il that coni sistel of a generally concave-convex disc-like Figure 2 is a Isection, on a larger scale. on the line 2, l of Figure 1;

Figure 3 is a top plan view of the valve shown in Figure 2;

Figure 4 is a section on the line I, l o! Figure 8, showing the valve in open position;

Figure 5 is a section similar to Figure 4 showing the valve in closed position;

Figure 6 is a bottom plan of the valve as viewed on the line 8-8 of Figure 5;

Figure 7 is a top plan view of another embodiment of the invention; and

Figure 8 is a section on the line l, l of Figure '1.

Referring now to the drawing, especially Figures l and 2 thereof, there is shown a safety inner tube comprising an outer tubular structure il.

composed o! elastic material such as rubber composition or the like, and an inner tubular structure il composed of impervious non-elastic ma terial such as rubberized fabric or the like. The

` tubes I0, ii are concentrically arranged. the tube two concentric circumferential compartments or chambers i3, H, of which chal-'uber I3 ls located entirely within the tube structure Il and chamber i4 is disposed exteriorly oi the structure Il and circumscribes the same. Communication between the chambers i8, il is edected by means of a relatively small apertureor port il in theI periphery of the tube structure Il, in the centrai plane of the inner tube. A single valve stem I6 of any usual or preferred construction is prostructure of :resilient rubber'composition that is formed with aV ilat vcircurnferential"'iiange Il. The valve member Il is mounted the Iinner surface of the inner tubular structure, concentrically of the port i! thereinf` theV flange I8 being bonded to the inhertube structure preferably by vulcanizatio'n,with the v'concave side of the valve confronting said port. Integrally formed on the concave side of the valvestructure is a cylindrical boss 120,' the plane face of which Vis disposed a vlittleto one side of the plane oi the attaching face of flange It, the arrangement being such that'normally the Vboss is in suillciently spaced relation to the port I5, as

' shown in Figures 2 and 4, as to enable the passage of air through the said port to the full limit of its capacity. 5

The efiective cross sectional area ofthe port l5 is such that when the boss 2l of the valve member Il is in its normally spacedposition, it will be at least as great as the effective cross sectional area of the passage inthe inilating valve stem il so that during inflation theair will ilow into the outer chamber Il as fast as the air enters chamber I3. This facilitates the iniiationprocedure and precludes a pressure differential between the two chambers during'iniiation which would give an incorrect indication ot the pressure in the chamber Il when the pressure is measured at'the intlating valve il. of the boss is formed with a shallow diametric groove 22 of smaller volumetric capacity than the port I5, for apurpos'e which presently .will be explained. Between the boss!! and :lange Il the concave-.convex portion o'fthe valve structure is formed with at least "one Vfaperimre or port 2|, which port is of smallerV capacity than port Il, but of larger capacity than groove 22. The weight oi the valve structure preferably is such as not to substantially unbalance the tire 'and tube assembly when placed opposite the valve stem I8, but is of such weight as'to hold the valve structure against the tube wall Ii when the wheel rotates at a predetermined or above, so that the valve i8 will be in a position to greatly restrict the ilow c! air from the inner chamber il to the outer chamber I4.

The invention operates as follows. When the improved inner tube is mounted in a tipe casing 'upon a vehicle, and the latter is stationary, theA valve structure isy in the position shown in Figures 2 and 4 of the drawing. Thus i! the inner tube is being inflated, air will pass readily Irom` The said plane face the inner chamber I3, through port 2I in valve I8 and through port I5 in inner wall II, into the outer chamber I4, thus establishing uniformity of pressure throughout the tube at once and facilitating the attainment of proper pressure. When the vehicle'is in motion and the tires are rotating, centrifugal force acting upon the valve structure I8 ilexes its concave-convex portion outwardly radially of the inner tube with the result that boss 20 moves into engagement with the tube-wall II, over the port I5, as shown in Figure 5, thus substantially closing oi communication between chambers I3, I 4 of the tube except as provided by the groove 22. Thus when a blowout occurs in a tire casing sustained by the improved inner tube, while the vehicle is in motion, the outer tube Wall I will be ruptured and the air inouter chamber I4 quickly will leave. This createsdiflerentlal air pressures in the inner and outer chambers I3, I4 such as to supplement the centrifugal force holding the valve in closed position. The air, slowly escaping by way of the groove 22, eventually will result in complete evacuation of the inner chamber I3, but not until sufficient time has elapsed to enable the vehicle to be brought to a stop. As soon as the vehicle is brought to a stop, the valve I8 is no longer subject to centrifugal force and as soon as the pressure in the chambers becomes more nearly equalized, it resumes the normal position shown in Figures 2 and 4, the remaining air in the limer chamber I3 thus being enabled quickly to escape.

From the foregoing it will be seen that the invention makes for safety in that a tire does not completely collapse in case of blowout but lli is able to provide adequate support to the vehicle until the latter can be brought to a stop. Thus the possibility of accident imperiling life and property is reduced to the minimum, rimcuttlng -of tires is avoided, and the driving of the vehicle upon a partly inflated tire for more than a short distance is prevented.

The embodiment of the invention designated and shown in Figure 6 and Figure 7 is essentially similar to that previously described, the concave-convex portion, the ange lila, and the gia being identical with similarly identiiied elements of the valve shown in Figures 2 and 5. The modified structure, however, differs in the internal construction or" the axial boss a, which weighted or loaded to insure a more positive action under the impetus of centrifugal force. To this end a cylindrical metal body 23, o brass cr other suitable metal is incorporated in the said boss by being molded therein, the side of the metal body nearest the port I5a being uncovered and exposed to said port. This face of the metal body is formed with a diametric groove 22a that serves the same purpose as the groove 22 of the previously described embodiment of the invention. The operation of the modied structure is identical to the operation of the structure previously described, but in a more efficient and superior manner since the metal structure 23 is not deformed by the pressures to which it is subject during use, and the diametric groove 20a maintains its normal size and capacity under all conditions.

Other modification may be resorted to without departing from the spirit of the invention, or the scope thereof as deiined by the appended claims.

What is claimed is:

l. A valve for an inflatable safety inner tube having an internal partition dividing the tube into concentric inner and outer air chambers, and a port in said partition providing communication between said chambers, said valve com-` prising a disc having a flexible concavo-convex medial portion formed with a marginal ange, the latter adapted for attachment throughout its area to the inner face of the partition, and surrounding the port therein, with theI concave side of the disc confronting said port, an axial boss formed on the concave side of the valvedisc normally adapted to stand in spaced relation to the said port but movable to close the same under the impetus of centrifugal force, a metal weight incorporated in said base, and a port in the concavo-convex portion of the disc.

2. A valve for an inflatable safety inner tube having an internal partition dividing the tube into concentric inner and outer air chambers, and a port in said partition providing communication between said chambers, said valve ccm- ;orising a disc having a exible ccncavo-convex medial' portion formed with a marginal flange, the latter ,adapted for attachment throughout its area to the inner face of the partition, concentrically of the port therein, with the concave side of the disc confronting said port, an axial boss formed on the concave side of the valvedisc normally adapted to stand in spaced rela- .tlon to the said port but movable to close the same under the impetus or centrifugal force, a metal weight incorporated in said boss and having an exposed face adapted to confront said port, and a port in the concavo-convex portion of thedisc. g

l CHARLES S. PIDGEON. 

